Double headed drill bit for a continuous coal mining machine

ABSTRACT

A double headed drill bit for a cutting element carried on a rotary drum member of a continuous mining machine is provided according to the invention. The drill bit is formed from a length of hardened material and includes a first tapered bit portion extending from a point located at a first end of the length of hardened material toward a mid-portion of the length of hardened material, and a second tapered bit portion extending from a point located at a second end of the length of hardened material toward the mid-portion of the length of hardened material. The drill bit is removably positioned within the central opening of an annular sleeve located in a block member mounted on the rotary drum member. One of the first tapered bit portion or second tapered bit portion extends outwardly from the annular sleeve and the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve. Positive retention means for securing the drill bit against longitudinal movement within the annular sleeve are also provided in the form of a retaining clip which engages an annular groove at the mid-portion of the drill bit.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to drill bits used in underground coal mining machines. More specifically, the present invention relates to a drill bit having two opposing bit heads and a new positive retention system for holding the bit in a sleeve.

Description of the Related Art

Continuous mining machines with drum type dislodging means are well-known and have been used for many years in the underground mining industry. A typical drum-type continuous mining machine 10 is shown in FIG. 1. The mining machine 10 includes a rotary drum member 12 carried on the forward end of a boom 14 of the continuous mining machine 10. The rotary drum member 12 carries multiple cutting elements 20, which are the subject matter of the present invention. A prior art cutting element 20 as best shown in FIG. 2 and FIG. 3 includes a block 22 which is mounted on the rotary drum member 12. The block 22 has a substantially cylindrical opening in a face thereof for receiving the shank portion (not shown) of a sleeve 24. As best shown in FIG. 2, the shank portion of the sleeve extends through the block 22 with the end of the shank extending slightly beyond the opening. The shank of the sleeve 24 and the opening the block 22 are dimensioned such that the shank may be securely press-fit into the block to prevent rotation thereof when in use.

The sleeve 24 also has a circular opening therein for receiving a drill bit 26. the drill bit 26 includes a shank portion 30 and tapered bit portion 32. a pocket in the end of the tapered bit portion 32 is configured to receive a drill bit insert 34, which is formed of a much harder material to withstand the pressure of drilling. An annular groove 36 is formed near the end of the shank 32 for receiving a spring clip 28 which secures the drill bit 26 against longitudinal movement relative to the sleeve 24.

The drill bit insert 34 and tapered bit portion 32 come into direct contact with the earth/rock/coal during mining with the continuous mining machine 10 and are subject to significant wear during use. On average, a drill bit 26 of the type shown in FIG. 2 and FIG. 3 costs between $15-$20. With each rotary drum member 12 carrying several dozen cutting elements 20, and with the drill bits 26 being subject to significant wear, there may be considerable cost in purchasing drill bits associated with a continuous mining machine such as the one shown in FIG. 1.

Accordingly, there is a need for a drill bit that is either less costly to manufacture, or that can be used longer, thus lowering the ultimate cost of use. As high strength steel is required to provide a durable drill bit, it is not a present possible to significantly reduce the cost by choosing different materials. Thus, there exists a need for a new drill bit configuration that will permit the bit to be used for longer periods of time thereby reducing the cost of replacing drill bits which must be done periodically.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a drill bit that has a longer useful drilling life than conventional drill bits.

It is also an object of the invention to provide a drill bit made of substantially the same material of prior art drill bits for substantially the same or similar cost, but that has a useful life of double that of current bits.

The present invention meets these objects by providing a double headed drill bit for use in a continuous mining machine. When a bit on one end of the double sided drill bit becomes worn, instead of discarding the bit and replacing it with a new one, the bit may be removed, turned over and inserted back into the sleeve such that the second bit is ready for use.

According to one presently preferred embodiment of the invention, there is provided a drill bit formed from a length of hardened material for use in connection with one or more cutting elements of a continuous coal mining machine. The drill bit according to this embodiment includes a first tapered bit portion extending from a point located at a first end of the length of hardened material toward a mid-portion of the length of hardened material. Similarly, a second tapered bit portion extends from a point located at a second end of the length of hardened material toward the mid-portion of the length of hardened material. Means for securing the drill bit within the cutting element of the continuous mining machine are also provided. The securing means according to this embodiment are located at the mid-portion of the length of hardened material.

The securing means according to this embodiment of the invention comprises an annular groove in the mid-portion of the length of hardened material. Positive retention means associated with the cutting element are also provided to prevent longitudinal movement of the drill bit relative to a body of the cutting element. First and second annular collars associated with the respective first and second tapered bit portions may also be provided such that the first and second annular collars are adjacent to and form the annular groove. Further, each of the first and second annular collars includes one or more outer cam surfaces configured to seat in and rotatably engage a surface of the cutting element. The positive retention means may include a retention clip which removably extends through one or more openings in the body of the cutting element and engages the annular groove of the drill bit to prevent longitudinal movement of the bit relative to the body of the cutting element. The retention clip may be substantially u-shaped and includes a first leg that extends though a first opening in the body of the cutting element and a second leg that extends through a second opening in the body of the cutting element.

The body of the cutting element may include a block member having a substantially cylindrical opening in a face thereof for receiving a shank portion of an annular sleeve, which includes a substantially circular opening therein for receiving the drill bit. The annular sleeve further includes a collar section that extends from the shank portion above the face of the block member such that the one or more openings in the body of the cutting element are located in the collar section of the annular sleeve. The shank portion of the annular sleeve may be securely press-fit into the block to prevent rotation thereof when in use.

The drill bit according to this embodiment of the invention may also be provided with hardened drill bit inserts located in a first cavity at the first end of the drill bit and a hardened drill bit insert located in a second cavity at the second end of the drill bit.

According to another aspect of the present invention, there is provided a cutting element carried on a rotary drum member of a continuous mining machine. The cutting element includes a block member mounted on the rotary drum member and having a substantially cylindrical opening in a face thereof, an annular sleeve having a central substantially circular opening extending through the length thereof and having a shank portion positioned within the cylindrical opening of the block member and a collar member extending from the shank portion above the cylindrical opening in the block member. A drill bit formed from a length of hardened material is also a part of this aspect of the invention. The drill bit includes a first tapered bit portion extending from a point located at a first end of the length of hardened material toward a mid-portion of the length of hardened material, and a second tapered bit portion extending from a point located at a second end of the length of hardened material toward the mid-portion of the length of hardened material. The drill bit is removably positioned within the central opening of the annular sleeve such that one of the first tapered bit portion or second tapered bit portion extends outwardly from the annular sleeve and the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve. Lastly, the cutting element according to this aspect of the invention is provided with positive retention means for securing the drill bit against longitudinal movement within the annular sleeve.

The cutting element for the continuous mining machine according to this second aspect of the invention may be further defined by the collar portion of the annular sleeve having one or more lateral opening extending through the collar portion such that the openings extend substantially perpendicular to a longitudinal axis of the drill bit. The drill bit may further include an annular groove in the mid-portion of the length of hardened material.

The positive retention means may include a retention clip which removably extends through the one or more lateral openings in the collar portion of the annular sleeve and engages the annular groove of the drill bit to prevent longitudinal movement of the bit relative to the body of the cutting element. The retention clip may be substantially u-shaped and may include a first leg that extends though a first opening in the collar portion of the annular sleeve and a second leg that extends through a second opening in the collar portion of the annular sleeve.

The cutting element for a continuous mining machine may further include a cylindrical end support configured to be inserted into the lower end of the sleeve. The cylindrical end support may have an outer surface that is configured to be rotatably received within the circular opening in the annular sleeve. The outer surface of the cylindrical end support also includes an annular groove configured to removably receive a clip therein for limiting the travel of the end support into the annular sleeve. An inner surface of the cylindrical end support may include a large opening area defined by a first tapered section followed by a vertical wall. The first tapered section may be configured to engage and support the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve. The cylindrical end support may further provide a means for removal of the drill bit if the bit breaks off at the shank.

These and other objects, features and advantages of the present invention will become apparent from a review of the following drawings and detailed description of the preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can best be understood in connection with the accompanying drawings. It is noted that the invention is not limited to the precise embodiments shown in the drawings, in which:

FIG. 1 is a side perspective view of a continuous mining machine according to the prior art.

FIG. 2 is a rear perspective view of a prior art cutting element associated with the continuous mining machine shown in FIG. 1.

FIG. 3 is a side exploded view of the prior art cutting element shown in FIG. 2.

FIG. 4 is a side exploded view of a double headed drill bit and sleeve assembly for a continuous mining machine according to a preferred embodiment of the present invention.

FIG. 5 is a side perspective view of the assembled double headed drill bit and sleeve assembly shown in FIG. 4.

FIG. 6 is a top end view in cutout of the collar section of the sleeve of the drill bit and sleeve assembly according to a preferred embodiment of the invention.

FIG. 7 is a sectional view of the sleeve shown in FIG. 6 along the line 7-7.

FIG. 8 is a top end view in cutout of the end support of the drill bit and sleeve assembly according a preferred embodiment of the invention.

FIG. 9 is a sectional view of the end support shown in FIG. 8 along the line 9-9.

DETAILED DESCRIPTION OF THE INVENTION

For purposes of promoting and understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and further modifications in the illustrated devices and described methods and further applications of the principles of the invention that would normally occur to one skilled in the art to which the invention relates.

As best shown in FIG. 4 and FIG. 5, one presently preferred embodiment of the invention comprises an improved drill bit 40, sleeve 50, retention clip 60 and end support 70. According to this embodiment of the invention, the improved drill bit 40 includes a first tapered bit portion 42 a at a first end thereof and a second tapered bit portion 42 b at a second end thereof. As with the prior art bit, each taped bit portion 42 a, 42 b includes a hardened drill bit insert 44 a, 44 b at its respective end. At the mid-portion of the double headed drill bit 40 there is provided an annular groove 45, the function of which will be described below. On either side of the annular groove 45, the respective opposing ends of the bit are provided with annular collars 46 a, 46 b. Each annular collar 46 a, 46 b has outer cam surfaces 47 a, 47 b and 48 a, 48 b that are configured to seat in corresponding cam surfaces 57, 58 of the sleeve 50 when the bit 40 is seated in the sleeve 50.

As best shown in FIG. 6 and FIG. 7, the sleeve 50 preferably includes a collar section 52 and a shank section 54. An annular groove 56 may be provided at the end of the shank section 54 to provide additional means for securing the sleeve within the block. As shown in FIG. 7, cam surfaces 57, 58 are provided within the central opening of the sleeve to engage the outer cam surfaces 47 a or 47 b and 48 a and 48 b of the drill bit 40 when the bit 40 is seated in the sleeve 50 as shown in FIG. 5. According to the preferred embodiment shown in FIG. 7, the first cam surface 57 is oriented at a 45 degree angle relative to the horizontal cross section of the sleeve 50 and the second cam surface is oriented at a 90 degree angle to the horizontal cross section. A pair of holes 59 a, 59 b are drilled through the collar section 52 of the sleeve 50. The location of the pair of holes 59 a, 59 b correspond to the position of the annular groove 45 of the bit 40 when it is properly seated in the sleeve 50. Positive retention of the bit 40 within the sleeve 50 is accomplished by way of retention clip 60 which passes through the pair of holes 59 a, 59 b in the collar section 52 and engage the annular groove 45 of the drill bit 40 to prevent longitudinal movement of the bit 40 relative to the sleeve 50. The profile of the collar section 52 of the sleeve 50 may be taller than the collar section of prior art devices to accommodate the clip 60. In addition, because the collar section 52 comes into direct contact with the surface to be mined, the taller collar also provides better wear characteristics. As shown in FIG. 7, the surface of the collar ring 52 is preferably at a 25 degree angle relative to the vertical outer ring of the collar, although other angles are certainly contemplated within the scope of the invention.

A preferred embodiment of the present invention may further include an end support 70 as best shown in FIG. 8 and FIG. 9. As best shown in FIG. 4, the end support 70 is configured to be inserted into the lower end of the sleeve 50 in the area of the annular groove 56. The end support 70 is cylindrical and has an outer surface 72 that is configured to be rotatable received within the circular opening in the sleeve 50. The outer surface 72 of the end support 70 also includes an annular groove 74 configured to removably receive a clip 80 therein. With the clip 80 located in the groove 74, the travel of the end support 70 into the sleeve 50 is limited. The inner surface of the end support 70 has a first tapered section 76 a, followed by a vertical wall 76 b that define a large opening area 78 of the end support 70. The inner surface then has a horizontal step region 76 c which transitions the inner surface into a second vertical wall 76 d that defines a small opening 79 in the lower end of the end support. The end support 70 serves to support the tapered end 42 a of the bit that is not being used and, as such is located within the circular opening of the sleeve 50. In addition, the end support provides a means for removal of the bit 40 if the bit breaks off at the shank.

This detailed description, and particularly the specific details of the exemplary embodiment disclosed, is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom, for modifications will become evident to those skilled in the art upon reading this disclosure and may be made without departing from the spirit or scope of the claimed invention. 

1. A drill bit formed from a length of hardened material for use in connection with one or more cutting elements of a continuous coal mining machine wherein the body of each of said one or more cutting elements comprises a block member having a substantially cylindrical opening in a face thereof for receiving a shank portion of an annular sleeve having a substantially circular opening therein for receiving said drill bit, said drill bit comprising: a first tapered bit portion extending from a point located at a first end of said length of hardened material toward a mid-portion of said length of hardened material; a second tapered bit portion extending from a point located at a second end of said length of hardened material toward said mid-portion of said length of hardened material; and means for securing said drill bit within said cutting element of said continuous mining machine, said securing means being located at said mid-portion of said length of hardened material.
 2. The drill bit of claim 1 wherein said securing means comprises an annular groove in the mid-portion of said length of hardened material and positive retention means associated with the cutting element to prevent longitudinal movement of the drill bit relative to a body of the cutting element.
 3. The drill bit of claim 2 further comprising first and second annular collars associated with the respective first and second tapered bit portions, said first and second annular collars being adjacent to and forming the annular groove.
 4. The drill bit of claim 3 wherein each of the first and second annular collars includes one or more outer cam surfaces configured to seat in and rotatably engage a surface of the cutting element.
 5. The drill bit of claim 2 wherein said positive retention means comprises a retention clip which removably extends through one or more openings in the body of the cutting element and engages the annular groove of the drill bit to prevent longitudinal movement of the bit relative to the body of the cutting element.
 6. The drill bit of claim 5 wherein the retention clip is substantially u-shaped and includes a first leg that extends though a first opening in the body of the cutting element and a second leg that extends through a second opening in the body of the cutting element.
 7. (canceled)
 8. The drill bit of claim 1 wherein the annular sleeve further includes a collar section that extends from the shank portion above the face of the block member such that said one or more openings in the body of the cutting element are located in the collar section of the annular sleeve.
 9. The drill bit of claim 8 wherein the shank portion of the annular sleeve is securely press-fit into the block to prevent rotation thereof when in use.
 10. The drill bit of claim 1 further comprising a hardened drill bit insert located in a first cavity at the first end of the drill bit and a hardened drill bit insert located in a second cavity at the second end of the drill bit.
 11. A cutting element carried on a rotary drum member of a continuous mining machine, said cutting element comprising: a block member mounted on said rotary drum member, said block member having a substantially cylindrical opening in a face thereof; an annular sleeve having a central substantially circular opening extending through the length thereof, said annular sleeve having a shank portion positioned within the cylindrical opening of the block member and a collar member extending from the shank portion above the cylindrical opening in the block member; a drill bit formed from a length of hardened material, said drill bit having a first tapered bit portion extending from a point located at a first end of said length of hardened material toward a mid-portion of said length of hardened material, and a second tapered bit portion extending from a point located at a second end of said length of hardened material toward said mid-portion of said length of hardened material, said drill be being removably positioned within the central opening of the annular sleeve such that one of the first tapered bit portion or second tapered bit portion extends outwardly from the annular sleeve and the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve; and positive retention means for securing said drill bit against longitudinal movement within said annular sleeve.
 12. The cutting element for a continuous mining machine according to claim 11, wherein said collar portion of said annular sleeve includes one or more lateral opening extending through the collar portion, said openings extending substantially perpendicular to a longitudinal axis of the drill bit.
 13. The cutting element for a continuous mining machine according to claim 12 wherein said drill bit comprises an annular groove in the mid-portion of said length of hardened material.
 14. The cutting element for a continuous mining machine according to claim 13 wherein said positive retention means comprises a retention clip which removably extends through said one or more lateral openings in the collar portion of the annular sleeve and engages the annular groove of the drill bit to prevent longitudinal movement of the bit relative to the body of the cutting element.
 15. The cutting element for a continuous mining machine according to claim 14 wherein the retention clip is substantially u-shaped and includes a first leg that extends though a first opening in the collar portion of the annular sleeve and a second leg that extends through a second opening in the collar portion of the annular sleeve.
 16. The cutting element for a continuous mining machine according to claim 11 further comprising a cylindrical end support configured to be inserted into the lower end of the sleeve.
 17. The cutting element for a continuous mining machine according to claim 16 wherein the cylindrical end support has an outer surface that is configured to be rotatably received within the circular opening in the annular sleeve.
 18. The cutting element for a continuous mining machine according to claim 17 wherein the outer surface of the cylindrical end support also includes an annular groove configured to removably receive a clip therein, said clip limiting the travel of the end support into the annular sleeve.
 19. The cutting element for a continuous mining machine according to claim 17 wherein an inner surface of the cylindrical end support includes a large opening area defined by a first tapered section followed by a vertical wall, said first tapered section configured to engage and support the other of the first tapered bit portion or second tapered bit portion extends into the shank portion the annular sleeve.
 20. The cutting element for a continuous mining machine according to claim 16 wherein the cylindrical end support provides a means for removal of the drill bit if the bit breaks off at the shank. 